Suppose that `z`  varies jointly with `x`  and `y` .

Find the constant of proportionality `k`  if `z = 113.4`  when `y = 2`  and `x = 7` .
`k =` 

Using the `k`  from above write the variation equation in terms of `x`  and `y` .
`z =` 

Using the `k`  from above find `z`  given that `y = 6`  and `x = 21` .
`z =` 



If needed, round answer to 3 decimal places.
Enter DNE for Does Not Exist, oo for Infinity